Method of making electrical transformer means

ABSTRACT

This disclosure relates to improved electrical transformer means which has heat transfer surface means for transferring heat outwardly from within electrical coil means of such transformer means to thereby provide optimum electrical performance and to an improved method of making such transformer means and associated coil means.

United States Patent [1 .1

Hoell [451 May 114, 1974 [5 METHOD OF MAKING ELECTRICAL 2,770,78511/1956 Haagens et a1. 336/61 TRANSFORMER MEANS 2,992,405 7/1961 Ursch336/61 X 2,592,817 4/1952 McKechnie.. 336/61 [76] Inven or: J h H l 3 9Glencross, 1,495,323 5/1924 Underhill 29/605 x Cincinnati, Ohio 452l73,170,225 2/1965 Gray et al. 29/605 [22] Filed: July 23, 1971 PrimaryExaminer-Charles W. Lanham [2| I Appl' l65730 Assistant ExaminerCarl E.Hall Related US. Application Data Attorney, Agent, or Firm-John G.Schenk [62] Division of Ser. No. 839,124, May 15, 1969,

abandoned.

- [57] ABSTRACT [52] CI g% This disclosure relates to improvedelectrical trans- [51] Int Cl Im1f7/06 former means which has heattransfer surface means [58] Fie'ld 61 for transferring heat outwardlyfrom within electrical 2 coil means of such transformer means to therebypr0- vide optimum electrical performance and to an im- 56] ReferencesCited proved method of making such transformer means and associated coilmeans. UNITED STATES PATENTS 3,086,184 4/1963 Nichols 336/207 X 10Claims, 26 Drawing Figures PATENTEDHAY '1 4 i974 SHEET 5 BF 7 FIG-I5METHOD OF MAKING ELECTRICAL TRANSFORMER MEANS This application is adivision of my application Ser. No. 839,124, filed May 15, 1969 nowabandoned.

This invention relates to electrical devices and more particularly tohigh performance electrical transformer means andto an improved methodof making same.

The market for electrical transformers such as transformers used inhousehold electrical devices is very competitive. Particularly in thecase of a transformer of the type used in a television set, for example,it is especially important that such transformer meet the requirementsof, providing continuous high quality electrical performance withoutoverheating, being of light weight, being of small size and beingcomparatively low in cost. Presently available transformers aredeficient in one or more of these requirements.

Accordingly, it is a feature of this invention to provide an improvedhigh performance electrical transformer which is of simple andeconomical construction.

Another feature of this invention is to provide such a transformer whichis light in weight and small in size when compared with presenttransformers providing equivalent electrical performance.

Another feature of this invention is to provide a transformerof thecharacter mentioned which has improved high performance coil means andsuch coil means includes means provided therein for transferring heatfrom within such transformer to the surrounding atmosphere to therebyprovide a cooler operating and hence more efficient transformer.

Another feature of this invention is to provide an improved electricalcoil meansparticularly adapted to be used in .an electrical transformerand having an improved metal heat transfer surface means fortransferring heat from the interior of such coil means to the exteriorthereof.

Another feature of this invention is to provide an improved method ofeconomically making a high performance electrical transformer.

Another feature of this invention is to provide an improved method ofmaking such economical and high performance transformer by providingsuch transformer with inexpensively produced and assembled heat transfersurface means for transferring heat from within such transformer to thesurrounding ambient atmosp here.

Another feature of this invention is to provide-an improved methodofmaking high performance electrical coil means particularly adapted tobe used in an electrical transformer.

Another feature of this invention isto provide an improved method ofmaking a plurality of such coil means in a simultaneous manner therebysubstantially reducing the cost thereof.

Therefore, it is an object of this invention to provide improvedelectrical transformer means and an improved method of making suchimproved transformer means having one or more of the novel features ofthis invention as set forth above or hereinafter shown or described.

Other objects, uses, and advantages of this invention are apparent froma reading of this description which proceeds with reference to theaccompanying drawings forming a part thereof and wherein:

FIG. 1 is a perspective view illustrating a plurality of threeelectrical coil means or coils comprising one embodiment of the improvedcoil of this invention which is adapted to be used to form an improvedelectrical transformer and showing such coils being wound simultaneouslyon rotatable spindle means and particularly illustrating the manner ofproviding integral spaced apart rectangular passage means in each coil.

FIG. 2 is a perspective view illustrating the rotatable spindle meanswithdrawn from within the coils of FIG. 1 after such coils have beencompletely wound and illustrating the three coils severed apart fromeach other to define individual units.

FIG. 3 is a perspective view illustrating a coil of FIG. 2 broken awayfrom associated core means prior to inse'rtion of metal heat transfersurface means within the passage means provided in such coil. 7

FIG. 4 is a perspective view illustrating one of the coils of FIG. 2inserted in position within associated transformer core means aridshowing a pair of metal heat transfer surface means or strips extendingin a rectilinear manner through associated elongated rectangular passagemeans provided in opposite ends of such coil means prior to forming suchstrips in position.

FIG. 4A is a perspective view showing the metal strips of FIG. 4 formedinto position so that their termi- .nal outer portions lie adjacentexposed outer surface means at each end of such core means and thusdefine a transformer subassembly ready for the installation of endcovers thereon.

FIG. 5 is a perspective view similar to FIG. 4A illustrating anotherembodiment of this invention also utilizing a coil of FIG. 2 to formanother transformer subassembly wherein a pair of preformedsubstantially Z- shaped heat transfer surface means are inserted inposition from each end of each rectangular passage means provided in theassociated coil.

FIG. 6 is a perspective view with parts broken away illustrating anotherembodiment of this invention which is similar to the embodiment of FIG.5 and which provides guide means within each rectangular passage meansto receive and support an associated pair of substantially Z-shaped heattransfer surface means.

FIG. 7 is an exploded perspective view showing one exemplary embodimentof the improved transformer of this invention comprised of thesubassembly of FIG. 4A with a pair of covers at opposite ends thereof.

FIG. 8 is a perspective view illustrating another trans formersubsassembly used to form another embodiment of the transformer of thisinvention and particularly showing the arrangement of the transformercore, coil, and a pair of elongated heat transfer surface means.

FIG. 9 is a side elevation of another embodiment of the improvedtransformer of this invention utilizing the transformer subassembly ofFIG. 8.

FIG. 10 is a view on the line 10-10 of FIG. 9.

FIG. 11 is a view on the line 11-11 of FIG. 9 rotated clockwise FIG. 12is a view looking perpendicular to the lefthand cover as illustrated inFIG. 9 of the drawings.

FIG. 13 is a view on the line 13-13 of FIG. 12.

FIG. 14 is a view on the line 14-14 of FIG. 12.

FIGflS is an enlarged fragmentary view showing a typical indentation orgroove provided in each side flange means of each cover to enableinsertion of elongated heat transfer surface means therethrough.

FIG. 16 is a fragmentary view similar to FIG. 12 and showing only thelower portion of the right cover provided on the transformer as shown inFIG. 9.

FIG. 17 is a perspective view illustrating a typical improved coil ofthis invention broken in half and showing the location of a plurality ofthermocouples in the center of such coil.

FIG. 18 is a perspective view similar to FIG. 1 of the drawingsillustrating a plurality of three electrical coils comprising anotherembodiment of the improved coil of this invention being woundsimultaneously on rotatable spindle means'and using a pair of metalinserts during the winding of such coil means to provide rectangularpassage means for later insertion of metal heat transfer surface meanstherewithin.

FIG. 19 is a view of the coils of FIG. 18 completely wound and showingthe metal spacers being withdrawn from within such coils.

FIG. 20 ilustrates the completed coils of FIG. 19 after having been cutwith suitable cutting means to define individual coils.

FIG. 21 is a perspective view similar to FIG. 8 particularlyillustrating the rectangular passage means in an individual'coil of FIG.20 after removal of the metal spacers and cutting to the desired length.

FIG. 22, is a perspective view similar to FIG. 18 and illustrating aplurality of three electrical coils being formed simultaneously using apair of severable spacer means to define rectangular passage means ineach coil.

, FIG. 23 is a perspective view showing the three coils of FIG. 22completely wound.

FIG. 24 illustratesthe coils of FIG. 23. being cut to define individualcoils and also showing that such spac ers are left withinthe coils andalso cut during the cutting process.

FIG. 25 is a perspective view illustrating one of the spacers beingremoved fromwithin an individual coil of FIG. 24 to leave a, rectangularpassage for insertion of heat transfer surface means therewithin.

While the various features of this invention are hereinafter illustratedand described as being particularly adapted for providing improvedelectrical transformer means and an improved method of making suchtransformer means such as, for example,'transformer means of the typeused in a television receiver, it is to be understood that the variousfeatures of this invention can be utilized singly or in any combinationthereof to provide transformer means for other uses and to provideimproved electrical coil means for other uses, as desired.

Therefore, this invention is not to be limited to only the embodimentsillustrated in the drawings because the drawings are merely utilized toillustrate examples of the wide variety of uses of this invention.

In the exemplary embodiment'of this invention illus trated in FIGS. 4Aand 7 of the drawings, an improved electrical transformer means such asa transformer designated generally by the numeral is illustrated.Transformer 30 in this example of the invention has a core designatedgenerally by the numeral 31 comprised of a plurality of laminated metalsheet means a representative few of which have been designated by thenumeral 32. Each metal sheet means 32 of this exemplary illustration iscomprised of a substantially E-shaped member and an l-shaped memberwherein the E- shaped members in adjoining sheet means 32 face inopposite directions in a known manner and for known reasons. 1

Transformer 30 has improved electrical coil means shown as an electricalcoil 33 supported therewithin and coil 33 has heat transfer surfacemeans shown as a metal heat transfer surface 34 extending from withincoil 33 to the exterior thereof for dissipating heat from within coil33. In this example of the invention a pair of transfer surfaces 34 isprovided so that each extends from an opposite end of coil 33 with suchcoil installed in position with core 31 in surrounding relation.

The installation of coil 33 in position within core 31 and the placementof the heat transfer surfaces 34 at opposite ends of coil 33 define atransformer subassembly which for convenience and ease of descriptionwill be designated by the numeral 35. The use of heat transfer surfaces34 and the simple manner of installing such surfaces in position in coil33 provide an efficient transformer which gives improved performance andis economical to construct as will be described in detail subsequently.

Housing means shown as covers and 41 are provided for transformer 30 andadapted to be installed in position at opposite ends of transformer 30.Each cover 40 and 41 is preferably fastened in position by a pluralityof four bolts each designated by the numeral 42.

Each bolt 42 extends through an associated opening 43 in cover 41, anopening 44 in laminated core 31, and a threaded opening 48 provided incover 40. After assemblying coil 33 within core 31 and inserting metalheat transfer surfaces 34 in position at each end of coil 33, covers 40and 41 are fastened in position to thereby define a compact easilyassembled transformer.

Coil 33 of this example is comprised of a number of layers which arewound starting at one edge and wound to the opposite edge it beingunderstood that each layer is wound one on top of the other startingfrom the center of such coil and winding out-wardly in a known manner.The electrical wire used in each layer of winding is preferablyinsulated by spray coating and suitable electrical insulation such astreated paper, or the like,

i is placed between adjoining layers.

The primary winding of transformer 30 is wound from one edge to theopposite edge as above described and is further preferably arrangedimmediately adjacent the center of the coil and wound outwardly, thesecondary winding is wound on top of the primary winding, and one ormore secondary filament windings may be wound on top of the secondarywinding of transformer 30, as desired and depending upon the particularapplication. The wire used for the various windings may be of copper,aluminum, or other suitable electrical conductor; as desired.

Core 31 in this example of the invention has a pair of exposed outersurface means each designated by the numeral 50 and each defining theopposite ends of core 31. Outer surface means 50 are arranged inparallel spaced apart relation and are each substantially planarsurfaces with the exception, of course, of opening means therein forreceiving portions of coil 33. Electrical coil 33 is supported withincore 31 so that a plurality of its winding layers are arranged outwardlyof exposed planar outer surface means or outer surface 50 at each endand such plurality of layers arranged outwardly of each surface 50 havebeen designated generally bby the numeral 51.

Coil 33 has preformed slot means shown as a pair of substantiallyrectangular slot or passage means designated by the numeral 52 providedadjacent each and thereof. Each slot 52 extends completely across thefull height, as designated by the numeral 53, of coil 33 and each slot52 is defined between a pair of adjoining layers of the windingscomprising coil 33. The construction and arrangement of core 311 andcoil 33 is such that each slot 52 is positioned so that it is arrangedoutwardly of an associated exposed planar surface 50.

In the embodiment of this invention illustrated in FIGS. 4A and 7 of thedrawings, a single strip of metal 34 extends beyond opposite ends ofslot 52 at each end of coil 33 and provides a means for transferringheat from within coil 33 to the exterior thereof. Each strip 34 isinserted in its associated rectangular passage 52 and extends completelythrough coil 33.

Passage 52 in this example of the invention is defined by a pair ofidentical insulating and spacing strip means shown as a pair of stripseach designated by the numeral 60 and each provided so as to extend thefull height of coil 33. Each strip 60 is formed as an integral part ofcoil 33 and is cut flush with the side edges of such coil. Cooperatingside surfaces of a pair of strips 60 define corresponding side surfacesof rectangular passage 52. v

Each strip 50 is of sufficient thickness so that the resultingrectangular slot 52 enables easy insertion. of strip 34 therethrough.The manner of forming coil-33 with strips 60 in position and the mannerof forming other coils capable of being used in the transformer whichare similar to coil 33 and which do not provide integral strips similarto strips 60 will be described in more detail subsequently.

As shown particularly in FIG. 4 of the drawings, each strip 34 isinserted in position in its associated slot 52 at each end of coil 33with its opposite ends extending beyond the sides of core 31 asillustrated. Suitable forming means is provided for forming and shapingthe outer ends of elongated strip 34 so that a portion 54 at each end isformed into position against outer surface 50 at each end as illustratedin FIG. 4A of the drawings. Each portion 54 lies against outer surface50 so the terminal end thereof lies flush with the associated side ofcore 31. The resulting transformer subassembly 35 is illustrated in FIG.4A and as a part of transformer 30 in FIG. 7 of the drawings.

Each cover 40 and 41 has recess means shown as a groove 55 defined ineach of its side edges.' Each groove 55 is adapted to receive anassociated portion 54 of strip 34 therethrough and thereby enable insidesurface means designated by the same numeral 56 on each cover 40 and 41to be held tightly against an associated outer surface 50 at each end oftransformer core 31.

Thus, it is seen that in this exemplary embodiment of the invention animproved coil 33 has been provided which has preformed slot means or apair of preformed rectangular passages 52 provided in its opposite ends.Each passage 52 extends substantially completely across each end of coil33 and each passage 52 is defined by a pair of spacing and insulatingstrips 60 which are integrally formed between a pair of winding layerswhere it is desired to provide each strip 34 for transferring heat fromwithin coil 33.

Another embodiment of this invention is illustrated in FIG. 5 of thedrawings wherein the transformer subassembly is practically identical tothe transformer subassembly 35; therefore, such transformer subassemblywill be designated generally by the numeral 35A and parts of subassembly35A which are identical to corresponding parts of subassembly 35 will bedesignated by the same numeral as subassembly 35 also followed by theletter designation A and not described again in detail. Only thosecomponent parts of subassembly 35A which are different fromcorresponding parts of subassembly 35 will be designated by a newnumeral also followed by the letter A" and described in detail.

In this example of the invention metal surface means used to transferheat from within coil 33A comprises a pair of metal strip means arrangedin coil 33A at each end thereof and each designated by the numeral 62A.Each metal strip means or metal strip 62A is supported within itsassociated passage 52A and extends outwardly from the center portion ofcoil 33A.

Each metal strip means or metal strip 62A in this example issubstantially Z-shaped with a portion thereof designated by the numeral63A lying adjacent, preferably against, an associated planar surface 50Aof core 31A. Each substantially Z-shaped strip 62A is preformed to theconfiguration illustrated in FIG. 5 of the drawings and such preformedstrip means is then inserted in position in an associated coil 33A.

Another exemplary embodiment of this invention is illustrated in FIG. 6of the drawings. In the embodiment of FIG. 6 the transformer subassemblyillustrated is practically identical to transformer subassembly 35A;therefore, such subassembly will be designated generally by the numeral358 and parts of subassembly 35B which are identical to correspondingparts of subassembly 35A will be designated by the same numeral as insubassembly 35A also followed by the letter designation B and notdescribed again in detail. Only those component parts which aredifferent fromm corresponding parts of subassembly 35A will bedesignated by a new numeral also followed by the letter designation Band described in detail.

The basic difference between subassembly 35B and subassembly 35A is thatguide means shown as a guide 653 has been provided as an integral partof subassembly 358. A guide 658 is preferably provided in coil 338 ineach end thereof and each guide is preferably made of a suitable rigidmaterial such as metal, or the like.

Guide 5513 is preferably inserted and formed as an integral part of coil338 during the forming of such coil and it will be appreciated that suchguide assures that heat transfer surfaces 62B may be easily inserted inposition without damaging the adjoining winding layers of coil 338.Guide 65B further assures that the rectangular passage means 52B doesnot collapse between spacers B and is particularly adapted to holdZ-shaped strips 628 in position.

Guide B has a flat main portion designated by the numeral 66B and a pairof hooking outer terminal ends designated by the numeral 678. Outer ends678 are arranged so as to overlap a part of the main portion 668 ofguide 65B along the top and bottom thereof and portions67lB are arrangedsubstantially coplanar and parallel to main portion 668. The distancebetween the inside surfaces of portions 67B and the inside surface ofmain portion 668 is such that each member 62B may be easily slid intoposition yet the clearance is sufficient within coil 338 so that itextends substantially across the major length of rectangular passage 52Band hence across what has been referred to as the height of coil 338.Each guide member is preferably adhesively fastened in position duringthe forming of coil 338.

It will be appreciated that each transformer subassembly 35A and 35Billustrated and described above may be substituted for the transformersubassembly 35 provided in the transformer assembly 30 of FIG. 7 tothereby provide a complete transformer unit. The differences in thetransformer subassemblies 35, 35A, and 35B have been described in detailabove and upon fastening the end covers 40 and 41 in position onsubassembly 35A or 35B the resulting transformer provides improvedperformance superior to presently known transformers. Furthermore, theunique and easily and economically provided heat transfer surface means34, 62A, and 628, for transformer subassemblies 36, 35A, and 358respectively assure efficient outward transfer of heat from within theirassociated coils.

Another exemplary embodiment of this invention is presented in FIGS.8-16 of the drawings wherein an improved transformer, transformersubassembly, and associated component parts are illustrated. Thetransformer subassembly of this latter embodiment, and shown in FIG..8,is practically identical to transformer subassembly 35 illustrated inFIG. 4A and 7 of the drawings; therefore, such transformer subassemblywill be designated generally by the numeral 35C and parts of subassembly35C which are identical to corresponding parts of subassembly 35 will bedesignated by the same numeral as' subassembly 35 also followed by theletter designation C and not described again in detail. Only thosecomponent parts which are different from correspondinng parts ofsubassembly 35 will be designated by a new numeral also followed by theletter designationC and described in detail.

Because ofits similarity to transformer 30, the complete transformer ofFIGS. 8-16 has been designated by the numeral 30C and the end covers andfastening means therefor of transformer 30C have been given new numeralsalso followed by the letter C and described in detail.

As seen in FIG. 8 of the drawings, transformer subassembly 35C has anelongated metal heat transfer surface means or strip extending throughits rectangular passage means 52C which is more than twice the length ofrectangular passage 52C and is designated by the numeral 70C. Each metalstrip 70C is adapted to be shaped or arranged such as by bending, orthelike, in an arcuate path, see FIG. 11, and fastened together adjacentits opposite terminal ends to define a substantially D-shaped tubularheat transfer surface means. The arcuate portion of such D-shaped heattransfer means is shown in FIG. 11 as being arranged outwardly.

with fastening means provided on the covers for transformer 30C tofasten each strip in position.

Each strip C provides an extended length heat transfer surfaces whichhas a neat appearance and yet is quite compact so as to assure theoverall size of transformer 30C is quite small. It will be appreciated,however, that in some applications of this invention it may be desiredto shape or cut or add additional surface means to metal strips 70C soas to provide even larger heat transfer surface areas for more efficientheat dissipation.

As seen particularly in FIG. 8 of the drawings, flux shield means shownas a flux shield 73C is provided over the top and bottom portion oftransformer subassembly 35C. The flux shield 73C has a width which issubstantially the same as the height 53C of coil 33C.

Insulating sleeve means is also provided around elongated metal strip70C and such insulating sleeve means is shown as a thin sleeve 75C whichis made of an insulating material such as rubber, or the like. Sleeve75C extends along the central portion of elongated strip 70C and is ofsufficient length that it will extend beyond the end cover meansprovided on transformer 30C as will be subsequently described in detail.The rubber sleeving 75C is used to thermally isolate each elongatedmetal strip 70C from core 31C and from adjoining cover means.

As seen particularly in FIGS. 12-16 of the drawings, cover means isprovided for covering both ends of transformer subassembly 35C. Thecover means comprises a left cover C, shown in FIGS. 12-15, and a rightcover 81C, illustrated in FIG. 16 of the drawings.

Left cover 80C has a plurality of four openings each designated by thenumeral 82C provided therein adjacent its corners and openings 82C areof a size and arrangement so as to be easily aligned in cooperatingrelation with a plurality of four openings each designated by thenumeral 44C provided in core 31C of transformer subassembly 35C.

Right cover 81C is basically identical to cover 80C with the exceptionthat cover 81C has an opening therein designated by the numeral 85C forextending electrical leads shown as a plurality of electrical wires at86C from within transformer 30C. Cover 81C has a plurality of fouropenings each designated by the numeral 87C and provided herein adjacentits four corners. Openings 87C of cover 81C are adapted to be placed inaligned relation with associated openings 44C at the opposite end oftransformer subassembly 35C.

With each set of openings 82C, 44C, and 87C in aligned relation at eachcorner of transformer 30C suitable fastening means such as a bolt 90C isprovided for extending through each associated set of openings to holdcovers 80C and 81C in position. Each bolt 90C cooperates with a threadednut 91C which in this example of the invention is arranged to bearagainst the outside surface of cover 81C to thereby clamp covers 80C and81C on opposite sides of the transformer subassembly 35C.

Each cover 80C and 81C has a preferably centrally arranged threaded studmeans or threaded stud designated by the numeral 92C. Each threaded studis fixed to its associated cover in any suitable manner as by welding,for example, and is adapted to receive an insulating sleeve 93C insurrounding relation thereabout and has a cooperating threaded nut 94Con its outer terminal end.

Each cover 80C and 81C has indentation means or a shallow groovedesignated by the-numeral 95C in each instance which is provided thereinalong its opposite side edges and illustrated in enlarged detail in FIG.of the drawings. Indentation 95C has a height corresponding to thecombined thickness of strip 70C and sleeve 75C so as to provide adequateclearance between each associated cover and core 311C.

The manner of utilizing each elongated strip 70C, which is over twicethe height of coil 33C, in a most efficient and compact manner isparticularly illustrated in FIGS. 8 and Ill ofthe drawings. Thus, asseen in FIG. 11, an insulating washer or sleeve 93C is first placed inposition around an associated stud. Each end of strip 70C is then passedthrough an associated groove 95C and bent around its associated endcover so that each opening 72C is placed in surrounding relation aroundstud 92C with a portion of each strip 70C bearing against and beingsupported against inward movement by sleeve 93C, the associated nut 94Cis then threaded in position against strip 70C. Of course, the sameprocedure is carried out at each end of transformer 30C.

Each insulating spacer 93C holds strip 70C in the desired spacedrelation at each end of the transformer 30C thereby assuring that thereis adequate air space at each end as shown at 96C to assure optimum heattransfer to the ambient atmosphere. Each elongated strip 70C is thusinstalled in position inexpensively.

As seen. in FIG. 11 of the drawings, the overall size of transformer 30Cis'comparatively small while the area of heat transfer surface utilizedat each end thereof is quite large and, of course, it is veryinexpensively made because it is produced, in effect, by an elongatedinexpensive strip that is bent to define the D- shaped tubular formillustrated. 7

'Thus, it is seen that transformer subassemblies 35, 35A, 35B, and 35Ceach utilize metallic heat transfer surfaces extending from associatedrectangular opening means provided in each end thereof to transfer heatfrom within their associated coils to the exterior thereof in aninexpensive and efficient manner. The heat transfer surface meansutilized in each embodiment of this invention may be made of anysuitable material and is preferably made of thin metal strip means.

Metal strip means containing copper or aluminum may be used effectivelyas heat transfer surfaces.

In each exemplary transformer subassembly illustrated and described inthis disclosure of the invention the core utilized is of standardconstruction which comprises layers of E and I sections suitably stackedtoge ther in a known manner and as previously mentioned and the overallperipheral outline of each core is in the shape of a parallelepiped.However, it will be appreciated that any shape and construction of coremay be used as desired.

Also, the exemplary transformers presented in this disclosure allutilize what is commonly referred to as shell-type core; however, theimproved manner of transferring heat from within the particulartransformer involved to the exterior thereof may also be effectivelyutilized in a core-type transformer or any other transformerconstruction not clearly of either of these two common types. In short,it is sufficient to provide a transformer coil structure of anyconfiguration and wherein such improved elongated slot'means is providedtherethrough for receiving an inexpensively produced metallic heattransfer surface means for transmitting heat from the interior of suchcoil structure to the exterior thereof.

An exemplary embodiment of improved electrical coil means of thisinvention and method of making same is illustrated in FIGS. 1 and 2'ofthe drawings wherein rotatable spindle means shown as a rotatablespindle 100 is provided to enable making a plurality, three in thisexample, of coils 33 in a simultaneous manner. Rotatable spindle 100 ispreferably of rectangular cross-sectional outline to correspond to thedesired rectangular opening to be provided in each coil 33.

Spindle 100 is rotated in any known suitable manner so as to wind layersof coils one on top of the other outwardly from the outer surface ofsuch spindle. Inasmuch as three coils are being wound simultaneouslythree sources of coil conductor material means or electrical wire areshown each designated by the numeral 102. Wires 102 are provided from asuitable source such as supply spool means which rotates simultaneouslywith spindle 1100 to unwind the wire being wound on each coil 33.

Each wire used in each coil 33 is preferably electrically insulated asby thin film insulation and suitable electrical insulation is providedbetween each layer of wire. The insulation provided between each layerof wire is preferably an insulation which is inexpensive and easily cutsuch as paper, or the like, which may be suitably treated. Each layer ofpaper insulation is designated by the same numeral 103 with only theouter easily visible layer being so designated in the drawings.

The coil winding method is quite simple and easy to achieveand in thisexample requires that a few inner layers of each coil 33 be wound. Thena plurality, four in this example, of elongated insulating and spacingstrips each designated by the numeral are placed in position against aninner winding at a predetermined point during the winding process.Suitable fastening means such as adhesive means'may be used toadhesively hold such strips in position.

The'outer windings for each coil are then wound so as to completely formeach coil 33. Each rectangular passage means 52 is defined in each caseby opposed layers of insulation 103 defining two opposed surfaces ofsuch passage and the remaining two surfaces of passage 52 being definedby strips 60. Each layer of paper insulation that is placed betweenadjoining coils 33 extends as a continuous sheet across all three coilsand the paper layers are simultaneously cut once the three coils 33 arecompletely defined.

' Suitable cutting means of any known type is provided for cuttingbetween adjoining coils 33 in this example of the invention to definethree individual coils. The cutting action is preferably achieved byrotary knife means and such cutting action does not tend to collapsepassages 52. Each coil 33 is then utilized with heat transfer surfacemeans of the type illustrated in FIGS. I

4A, 5, 6, and 8 of the drawings to provide an improved transformer ofthis invention.

The particular locations in each coil 33 at'which the rectangularelongated slots 52 are provided will vary in each particular applicationof this invention. However, it will be appreciated that each rectangularslot is generally provided approximately centrally across the thicknessof the particular windings or layers provided in any individual coil atthe point of maximum heating and thereby is able to transfer heat fromthe interior of such coil to the exterior thereof in a most efficientmanner.

Another exemplary embodiment of the improved coil -means of thisinvention and method of making same is illustrated in FIGS. 18-20'of thedrawings. The coils of this latter embodiment are practically identicalto coils 33 with the exception that spacers 60 which are an integralpart of each coil 33 have been eliminated; therefore, such coils will bedesignated by the numeral 33 followed by the letter designation M.Component parts of each coil 33M and illustrated components for isproviddd at opposite sides of coils 33M which are being simultaneouslywound in the same manner as coi-ls 33..Each member has an opening 111Mtherein adjacent one end thereof.

A few inner layers of each coil33M are first wound in position then ateach location where it is desired to provide a rectangular slot 52M ametal spacer 110M is placed in position and the remainder of the coil33M wound as desired. In this example two rigid members 110M are usedand once the winding is completed such members are removed as shown inFIG. l9by inserting a suitable tool through openings 111M and pulling.Coils 33M are then cut apart so as to define the three individual coils.

Each coil 33M may be used interchangeably with coil 33 as used in allpreviously presented embodiments of this invention and, of course, it isonly necessary to insert the appropriate metallic heat transfer surfacemeans within an associated slot 52M.

Another exemplary embodiment of this invention is illustrated in FIGS.22-25 of the drawings wherein a plurality of three coils'each designatedby the numeral 33N are formed simultaneously in a similar manner ascoils 33M and coils 33N after being formed are identical to coils 33M;therefore, as inthe previous example, coils 33N and components used tomake such coils will bear the same numerals as corresponding componentsof the next previous embodiment also followed by the letter designationN in this letter embodiment.

The spacing inserts 1l0N used to make slots 52N in each coil 33N aremade of a severable material such as a thick cardboard, or the like. Afew layers of wire are wound on spindle 100N as seen in FIG. 22,severable inserts 110N are then suitably held in position, then theremainder of each coil33N is wound in a simultaneous manner by rotatingspindle 100N. After the coil is completely defined it will appear asillustrated in FIG. 23 of the drawings.

Suitable cutting means shown as rotary cutting means 113N is providedfor cutting through the elongated wound structure of FIG. 23 to define aplurality of three individual coils 33N. Each individual coil 33N is cutwhile also cutting spacers llN and such spacers remain in each coil 33N.

Tool means such as a rod 1 MN is provided for pushing cut each severedcardboard spacer and withdrawing it. This procedure is carried out asshown in FIG. 25 so as to withdraw the spacers from each coil 33N andthereby define the rectangular passage means 52N.

Each coil 33N may be utilized in the same manner and in all embodimentsof the invention as previously illustrated and described in connectionwith coil 33.

While a plurality of three coils have been illustrated and described asbeing made in a simultaneous manner in three examples of making coilspresented in this disclosure, it will be appreciated that any number ofcoils may be made simultaneously and that it is merely necessary toprovide a rotatable spindle of proper size and a suitable number of leadin wires. The method of this invention may be used to make a dozencoils, for example, in a simultaneous manner. Obviously a single coilmay be made also, if desired, using the technique described above todefine passage means for the heat transfer surface means.

Thus, it is seen that an improved method has been shown for making coilseach having substantially rectangular passage means therein forreceiving and supporting heat transfer surface means adapted to beinserted therein to transfer heat from within each coil to the exteriorthereof. Furthermore, it will be appreciated that this invention enablesthe forming of such high performance coils in an economical manner andsuch coils may be used not only in transformer application but in otherapplications where it is desired to provide cool operating highperformance coils.

Considerable tests have been conducted to establish the effectivelnessof the improved and simply made and installed heat transfer surfacemeans of this invention and to illustrate the gains to'be made byutilizing such heat transfer means. It has been shown, for example, thatupon designing a transformer within specified performance requirements,the improved heat transfer surface means of this invention and themethod of forming same make it possible to design a cooler operatingmore efficient transformer. The net effect is that this invention makespossible delivery of a transformer to given customer requirements whichis lighter in weight, smaller in size, uses less materials, and thusresults in a comparatively less expensive transformer.

A series of tests conducted to verify the improved effectiveness of theheat transfer surface means of this invention was conducted in whichvarious coils had thermocouples installed at six positions as shown inFIG. 17 of the drawings. Identical coil structures were used in theassociated transformers that were tested and such transformers wereidentical except they were modified as indicated in the following tableand under test conditions as presented therein. The reference to casedmeans that end covers were fastened in position on each coil and theimpregnated transformers were impregnated with a suitable knownmaterial. The thermocouples were placed at positions designated by thenumerals R through W in FIG. 17.

Test Conditions: E.I.A. heat chamber 40 C ambi- SWP- Input voltage V 60Cycles AC power Secondary loaded.

Ends of heat transfer surfaces were bonded between core and case.

Test No. l 2

lmpregnated No No Cased Yes Yes Metal Heat Transfer Surface No YesThermocouple Position Temperature in Degrees Centigrade R. Betweeninside insulating layer and Core 119 112 S. Between inside insulatinglayer and First layer (L) of Primary (Pri) 141 127 T. Between 3L and 4Lof Pri. l7 136 U. Between Fri. and Secondary (Sec.) 153 l 19 V. Between3L and 4L of Sec. 147 I27 W. Between Sec. and Sec.

Filament [33 121 Thus, it will be seen from the above table that byusing the improved heat transfer surface means of this invention loweroperating temperatures were encountered at all locations within theparticular coils tested and particularly near the center portions ofeach coil.

Terms such as top, bottom, upper, lower, sides, ends, and the like, havebeen used in this disclosure for ease of description and merely todescribe the positions of various components of the transformers andtransformer subassemblies as illustrated in the drawings and such termsshould not be considered as limiting the scope of this invention in anyway.

Thus, it is seen that this invention provides improved transformer menswhich is of simple and economical construction and which is of lightweight and small size as compared to existing transformer means.

Further, this invention provides an improved method of making suchtransformer means.

While the form of the invention now preferred has been disclosed ayrequired by statue, other forms may be used, all coming within the scopeof the claimed subject matter which follows.

What is claimed is:

l. A method of making an improved electrical transformer comprising thesteps of, providing metal core means having exposed outer surface meansat opposite ends of said core means, providing electrical coil meanyhaving a plurality of winding layers adapted to be supported exteriorlyof said exposed outer surface means, forming slot means between a pairof adjoining layers of said plurality of layers, said slot meansextending across the full height of said coil means, supporting saidcoil means within said metal core means with said slot means arrangedexteriorly of said exposed outer surface means, providing metal heattransfer means, and placing said metal heat transfer means within saidslot means, whereby said metal heat transfer means extends outwardlyfrom said slot means and transfers heat from within said assembledtransformer to the exterior thereof to provide an improved moreefficient transformer.

2. The method as set forth in claim 1 in which said step of providingmetal heat transfer means comprises providing metal strips and saidplacing step comprises extending said metal straps from opposite ends ofsaid slot means beyond associated opposite ends of said coil means.

3. The method as set forth in claim 2 in which said step of forming slotmeans comprises forming substantially rectangular passage means in saidcoil means which extends completely across said coil means between saidpair of adjoining layers and said placing step comprises extending saidelongated metal strips beyond opposite ends of said rectangular passagemeans and hence beyond associated opposite ends of said coil means.

4. The method as set forth in claim 3 in which said step of providingelongated strips comprises providing a single elongated flat metalstrip, said placing step comprises inserting said elongated metal stripso that it extends completely through said rectangular passage means andexteriorly of opposite coil ends thereof, and comprising the furtherstep of shaping both opposite strip ends thereof so they lie adjacentsaid outer surface means.

5. The method as set forth in claim 4 in which, said step of providing asingle elongated flat metal strip comprises providing an elongated stripwhich is more than twice the length of said rectangular passage means,said shaping step comprises shaping the opposite ends thereof so eachextends in an arcuate path, and comprising the further step of fasteningsaid ends together to define a tubular substantially D-shaped metal heattransfer means.

6. The method as set forth in claim 5 comprising the further steps of,providing cover means adapted to enclose said plurality of layers,fastening said cover means against said exposed outer surface means toenclose said metal plurality of layers, and fastening said strip endsagainst said cover means during said shaping step.

7. The method as set forth in claim 3 in which said step of providingmetal strips comprises providing a pair of metal strips and said placingstep comprises inserting each of said metal strips from opposite ends ofsaid rectangular passage means so that they abut each other adjacent thecenter portion of said passage means.

8. The method as set forth in claim 7 comprising the further step of,shaping each of said pair of metal strips prior to inserting each ofsaid strips in position during said placing step so as to define asubstantially Z- shaped metal heat transfer means, and said placing stepfurther comprises placing a portion of each of said strips adjacent saidouter surface means.

9. The method as set forth in claim 7 further comprising the steps of,providing guide means adapted to hold said pair of metal strips inposition, supporting said means within said rectangular passage means,and said placing step comprises'inserting each of said strips fromopposite ends of said rectangular passage means into said guide means.

10. The method as set forth in claim 1 in which said placing stepfurther comprises arranging said metal strips immediately adjacent saidouter surface means, and comprising the further steps of providing covermeans adapted to be fastened against said outer surface means andfastening said cover means against said outer surface means with saidmetal strips having its opposite ends arranged between said cover meansand said outer surface means.

1. A method of making an improved electrical transformer comprising thesteps of, providing metal core means having expOsed outer surface meansat opposite ends of said core means, providing electrical coil meanyhaving a plurality of winding layers adapted to be supported exteriorlyof said exposed outer surface means, forming slot means between a pairof adjoining layers of said plurality of layers, said slot meansextending across the full height of said coil means, supporting saidcoil means within said metal core means with said slot means arrangedexteriorly of said exposed outer surface means, providing metal heattransfer means, and placing said metal heat transfer means within saidslot means, whereby said metal heat transfer means extends outwardlyfrom said slot means and transfers heat from within said assembledtransformer to the exterior thereof to provide an improved moreefficient transformer.
 2. The method as set forth in claim 1 in whichsaid step of providing metal heat transfer means comprises providingmetal strips and said placing step comprises extending said metal strapsfrom opposite ends of said slot means beyond associated opposite ends ofsaid coil means.
 3. The method as set forth in claim 2 in which saidstep of forming slot means comprises forming substantially rectangularpassage means in said coil means which extends completely across saidcoil means between said pair of adjoining layers and said placing stepcomprises extending said elongated metal strips beyond opposite ends ofsaid rectangular passage means and hence beyond associated opposite endsof said coil means.
 4. The method as set forth in claim 3 in which saidstep of providing elongated strips comprises providing a singleelongated flat metal strip, said placing step comprises inserting saidelongated metal strip so that it extends completely through saidrectangular passage means and exteriorly of opposite coil ends thereof,and comprising the further step of shaping both opposite strip endsthereof so they lie adjacent said outer surface means.
 5. The method asset forth in claim 4 in which, said step of providing a single elongatedflat metal strip comprises providing an elongated strip which is morethan twice the length of said rectangular passage means, said shapingstep comprises shaping the opposite ends thereof so each extends in anarcuate path, and comprising the further step of fastening said endstogether to define a tubular substantially D-shaped metal heat transfermeans.
 6. The method as set forth in claim 5 comprising the furthersteps of, providing cover means adapted to enclose said plurality oflayers, fastening said cover means against said exposed outer surfacemeans to enclose said metal plurality of layers, and fastening saidstrip ends against said cover means during said shaping step.
 7. Themethod as set forth in claim 3 in which said step of providing metalstrips comprises providing a pair of metal strips and said placing stepcomprises inserting each of said metal strips from opposite ends of saidrectangular passage means so that they abut each other adjacent thecenter portion of said passage means.
 8. The method as set forth inclaim 7 comprising the further step of, shaping each of said pair ofmetal strips prior to inserting each of said strips in position duringsaid placing step so as to define a substantially Z-shaped metal heattransfer means, and said placing step further comprises placing aportion of each of said strips adjacent said outer surface means.
 9. Themethod as set forth in claim 7 further comprising the steps of,providing guide means adapted to hold said pair of metal strips inposition, supporting said means within said rectangular passage means,and said placing step comprises inserting each of said strips fromopposite ends of said rectangular passage means into said guide means.10. The method as set forth in claim 1 in which said placing stepfurther comprises arranging said metal strips immediately adjacent saidouter surface means, and comprising the further steps of providing covermeans adapted to be fastened against said outer surface means andfastening said cover means against said outer surface means with saidmetal strips having its opposite ends arranged between said cover meansand said outer surface means.